As mentioned earlier, Actuate BIRT Designer uses Highcharts, a third-party charting library, to render HTML5 charts. To create a JavaScript chart theme, you set the Highcharts chart options to values that provide the visual attributes you desire. Every option has a default value. You define attributes only to change default settings, or to add items that do not appear by default.

Listing 15-1 shows the JavaScript code for the predefined chart theme, Chart Grid. The charts in Figure 15-2 and Figure 15-3 use this theme. As the code shows, options are set using a JavaScript object notation structure. Keys and values are connected by colons, separated by commas, and grouped by curly brackets.